Clinical value of prolactin bioassay in euprolactinemic reproductive disorders

To examine the disparity between clinical presentation and prolactin (PRL) measured by radioimmunoassay (RIA), serum samples from 128 patients with galactorrhea and/or reproductive disorders were evaluated by RIA for immunoassayable PRL (RIA-PRL) and by Nb2 lymphoma cell proliferation assay for bioassayable PRL (bioassay-PRL). One hundred fifteen patients had normal RIA-PRL and 13 patients had high RIA-PRL (greater than 25 ng/ml). Twenty patients had galactorrhea, two of whom had hyperprolactinemia. The reproductive disorders in female patients included infertility, amenorrhea, oligomenorrhea, irregular menstrual cycles, and luteal phase defects. Six oligospermic males also were studied. Twenty-three male and female volunteers with no evidence of reproductive disorders served as controls. Appropriate comparisons showed that PRL bioassay/RIA ratio, an index of agreement between the two assay systems, did not differ for the various patient groups compared with controls. It is concluded that Nb2 lymphoma bioassay does not provide additional diagnostic value to RIA in defining the cause of euprolactinemic galactorrhea and/or reproductive disorders.